(a) Technical Field
The present invention relates to a sputtering method using a sputtering device, and more particularly to a sputtering method using a sputtering device, wherein scan region of a magnet, which scans the undersurface of a sputtering target is defined as some part of the divided entire scan region of sputtering target and is applied in sequential order.
(b) Description of the Related Art
Generally, a sputtering device is widely used in forming thin films on substrates for semiconductor elements or substrates for Liquid Crystal Display devices.
FIG. 1 is an overview of a sputtering device. Referring to FIG. 1, the sputtering device is characterized by comprising a suscepter 102, in which a substrate 103 is installed within a vacuum chamber 101, a metal sputtering target 104, which is employed as deposition source on the opposite surface of the substrate 103.
The sputtering target 104 herein is fixed by a back plate 105 to provide materials for thin films to be formed on the substrate 103, a ground shield 106 is prepared along the side of the sputtering target 104, a mask 107 is prepared along the periphery of a gap between the substrate 103 and the sputtering target 104.
A magnet 108 to allow DC power is attached to the undersurface of the back plate 105 by a driving means 109, such that the magnet can scan back and forth the sputtering target 104.
In such a state, if inert gas argon (Ar) is supplied into the vacuum chamber 101, and DC bias is powered to the sputtering target 104, the inert gas is transformed to a state of ionized plasma, which leads to ions colliding with the sputtering target 104, and thin films are formed on the substrate 103, with the sputtering target 104 emitting atoms.
At this point, the magnet 108 provides magnetic field by scanning back and forth the sputtering target 104, as shown in FIG. 2, thereby, inducing the ions to collide with the sputtering target 104.
Conventionally, however, in a scanning motion of the magnet 108, scanning speed is supposed to decrease at left side and right side of the sputtering target 104, allowing the magnet to stay at left side and right side relatively longer than at center part. If the magnet 108 is in a stationary state for long, the duration of exposure to the magnetic field gets longer at left side and right side than at center part of the scan region D of the magnet 108.
Namely, erosion occurs relatively more at the left side and the right side where the duration of exposure of the magnet 108 of the sputtering target 103 gets relatively long than at the center.
FIG. 3 is a cross-section view along I-I′ line in FIG. 2. Referring to FIG. 3, it may be observed in sputtering target A that the thickness t3 at either side is smaller than the thickness t2 at the center part, which means the either side have been eroded more than the center part.
Consequently, the utilization efficiency of the sputtering target of a sputtering device is lessened because erosion is concentrated on left side and right side than on center part.
In addition, a changing term of a sputtering target gets faster depending on the lessened utilization efficiency.
Furthermore, as the changing term of the sputtering target gets faster, manufacturing cost of forming thin film on substrate would correspondingly increase.